Hi all I'm a long time Mandrake user and am the person responsible for the base patch in the multimedia kernel and all the interactivity changes that have gone into the 2.6 development kernel (from 2.6.0-test6). A couple of years ago when I was subscribed to this list I suggested renicing X by default to -10 and noticed that it was done on the following release by default. That was a recommendation based on the default kernel's scheduler inability to make X smooth enough under load.
However I am going to have to recommend reversing that change now as the new kernel has been tuned to allow good performance of X at nice 0. The new O(1) scheduler is far more aggressive with treatment of priorities and has much larger timeslices. Giving X a priority of -10 will make it cause unnecessary scheduling latencies for tasks that use even small amounts of cpu such as audio playback. In a nutshell this means that renicing X will make audio skip with a 2.6 kernel on even modern hardware. Please CC me in any replies as I'm no longer subscribed to cooker. Cheers, Con